Pedal lever bicycles have been proposed heretofore, and arrangements have been suggested for changing the ratio of power applied to the driving chains for the bicycles. However, these gear changing arrangements have often been manually operable, or have not been positive in their mode of locking into the new power or gear ratio. Also, in some cases, the mechanical mechanism has been unduly complex and not readily susceptible of mass production. Accordingly, an important object of the invention is to improve and simplify the gear or ratio changing mechanisms of pedal lever type bicycles.
In pedal lever bicycles, particularly when the pedal levers are to be actuated independently of one another, the problem of maintaining the driving chain under substantially constant tension raises certain problems, because the chain will normally move in the order of 8 to 19 inches. If the chain is connected to a spring which is secured to the frame of the bicycle, therefore, either a constant force spring must be used, or a considerable increase in tension and loss of power is caused when the conventional extension spring is elongated. Further, the use of a constant force spring is subject to some problems, as these springs are not inexpensive, and can come out of adjustment, and have limited fatigue life.
Accordingly, another object of the invention is to improve the arrangements for maintaining the driving chains in a pedal lever bike under proper, substantially constant tension.